Baseline Model Calibration and Validation Report Ventura River Watershed Hydrology Model Prepared for: Ventura County Watershed Protection District Ventura, CA Prepared by: 1230 Columbia St., Ste. 1000 San Diego, CA 92101 Tel 619-702-6059 • Fax 619-525-7186 July 21, 2009 Ventura River Model Baseline Report July 21, 2009 Table of Contents List of Tables ................................................................................................................................. iv List of Figures................................................................................................................................ vi Executive Summary....................................................................................................................... xi 1 Introduction...............................................................................................................................1 1.1 Scope of this Report.....................................................................................................................................1 1.2 Role of Model Calibration and Validation...................................................................................................1 1.2.1 Objectives of Model Calibration Activities.........................................................................................2 1.2.2 Hydrologic Validation Procedures ......................................................................................................2 2 Meteorology..............................................................................................................................5 2.1 Data Sources ................................................................................................................................................5 2.1.1 Precipitation ........................................................................................................................................5 2.1.2 Evaporation Data...............................................................................................................................13 2.1.3 Air Temperature ................................................................................................................................14 2.2 Interfacing with the HSPF Model ..............................................................................................................15 3 Hydrologic Response Unit Representation.............................................................................17 3.1 Land Use ....................................................................................................................................................17 3.2 Impervious Cover.......................................................................................................................................21 3.3 Soil Hydrologic Group and Slope ..............................................................................................................22 3.4 Irrigation Water Supply..............................................................................................................................25 3.4.1 Irrigation Demand .............................................................................................................................25 3.4.2 Irrigation Application ........................................................................................................................28 3.5 Fire Impacts................................................................................................................................................29 3.5.1 Simulation Approach for Burned Land .............................................................................................29 3.5.2 Fire History .......................................................................................................................................31 3.6 Watershed Segmentation............................................................................................................................38 3.7 Summary of the HRU Development Process .............................................................................................45 3.8 Assignment of Meteorology to HRUs........................................................................................................48 4 Hydraulic Routing Network ...................................................................................................51 4.1 Stream Segmentation .................................................................................................................................51 4.2 Functional Representation of Hydraulics (FTables)...................................................................................57 i Ventura River Model Baseline Report July 21, 2009 4.2.1 Use of HEC Flood Elevation Models................................................................................................57 4.2.2 Regional Curve Fitting ......................................................................................................................58 4.3 Reservoirs...................................................................................................................................................60 4.4 Debris and Detention Basins......................................................................................................................63 4.5 Diversions and Withdrawals ......................................................................................................................64 4.6 Stream Reach Interactions with Groundwater............................................................................................67 4.7 Point Source Inputs ....................................................................................................................................71 4.8 Final Reach Models....................................................................................................................................72 5 Hydrologic Model Calibration and Validation Approach ......................................................73 5.1 Hydrologic and Hydraulic Calibration Procedures ....................................................................................73 5.1.1 HSPF Hydrology Algorithms............................................................................................................73 5.1.2 Parameter Inference from Data..........................................................................................................74 5.1.3 Calibration Process............................................................................................................................75 5.2 Performance Criteria ..................................................................................................................................81 5.3 Sensitivity and Uncertainty Analyses.........................................................................................................82 5.3.1 Sensitivity Analysis...........................................................................................................................82 5.3.2 Uncertainty Analysis .........................................................................................................................82 6 Hydrologic Calibration and Validation Results......................................................................85 6.1 Calibrated Parameters ................................................................................................................................85 6.2 Model Calibration Summary......................................................................................................................87 6.3 Model Validation Summary.......................................................................................................................90 6.4 Water Balance Summary............................................................................................................................93 6.5 Detailed Calibration Results.......................................................................................................................99 6.5.1 Matilija Creek above Reservoir (603A) ............................................................................................99 6.5.2 Matilija Creek below Dam (602/602A)...........................................................................................104 6.5.3 North Fork Matilija (604)................................................................................................................104 6.5.4 Ventura River near Meiners Oaks (at Robles Diversion) (607) ......................................................109 6.5.5 San Antonio Creek at Hwy. 33 (605) ..............................................................................................113 6.5.6 Ventura River near Ventura (at Foster Park) (608) .........................................................................118 6.5.7 Coyote Creek near Oak View (600) ................................................................................................122 6.5.8 Santa Ana Creek near Oak View (606A) ........................................................................................127 6.6 Detailed Validation Results......................................................................................................................131 6.6.1 Matilija Creek below Dam (602/602A)...........................................................................................131